import java.util.*;

public class Main{
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int m = in.nextInt();
        
        double a = 1.0;
        for (int i = n; i > m; i--) {
            a *= i;
        }
        for (int i = n-m; i >= 1; i--) {
            a /= i;
        }
        a *= Math.pow(0.8, m);
        a *= Math.pow(0.2, (n-m));
        System.out.printf("%.4f", a);
    }
}